Semiconductor integrated circuit device with power consumption reducing arrangement

ABSTRACT

In semiconductor circuits, and particularly in memories, it is often desirable to use bipolar transistors for speed together with MOS elements. However, although the bipolar transistors are useful for speed considerations, they undesirably significantly increase the power consumption of the overall circuit. Accordingly, to reduce power consumption, a bipolar/MOSFET arrangement is provided wherein MOSFETs are used as current sources to supply operation currents to the bipolar transistors only during the periods of their operation. Thus, a semiconductor integrated circuit device is achieved featuring a high operation speed yet consuming reduced amounts of electric power. Additionally, power consumption can be further reduced by providing a time serial operation for actuation of the MOSFETs in different peripheral circuits for a memory array.

This application is a continuation of application Ser. No. 259,459,filed on Oct. 14, 1988, now abandoned, which is a continuation ofapplication Ser. No. 686,600, filed on Dec. 26, 1984, now abandoned.

FIELD OF THE INVENTION

The present invention relates to a semiconductor integrated circuitdevice, and particularly to a technique that can be effectively adaptedto, for instance, CMOS (complementary MOS)-type or bipolar-type staticRAMs (random access memories).

BACKGROUND OF THE INVENTION

It has been known to employ bipolar transistors for reading/wiringcircuits and digit line select circuits, in order to increase theoperation speed of CMOS static RAMs. For example, such an arrangementhas been disclosed in Japanese Patent Laid-Open No. 58193/1981.

In such a semiconductor memory device, since an operation (bias) currentis supplied at all times to the bipolar transistor, the current consumedbecomes a very large value. Therefore, there arises a serious defectdirected in that it is impractical to have a battery back-up operation,even though a great merit of a CMOS static RAM is the fact that such abattery back-up operation is generally available. In the readingcircuit, furthermore, a bipolar transistor is used as a column switchingcircuit, and a current is supplied to a memory cell that is selected viathe column switching circuit to obtain a reading signal. However, thevalue of reading current cannot be increased since it is determined bythe conductance of MOSFET in the memory cell. This is because, althoughthe element size must be increased to increase the reading current, itis not allowed to increase the element size of the memory cells from thestandpoint of increasing the memory capacity. Therefore, despite thefact that the bipolar transistors are employed, the reading speed of theabove-mentioned conventional semiconductor memory device cannot be soincreased. Further, since the column switching circuit is constituted bythe bipolar transistors, it becomes difficult to set the level(select/non-select levels) of output signals of the column addressdecoder circuit.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a semiconductorintegrated circuit device which accomplishes a high operation speedwhile preventing the generation of ineffective current.

Another object of the present invention is to provide a CMOS static-typeRAM which accomplishes a high operation speed without impairing theadvantage of low power consumption of the CMOS circuit.

A further object of the present invention is to provide a bipolar RAMwhich helps greatly reduce the consumption of electric power.

The above and other objects as well as novel features of the presentinvention will become obvious from the description of the specificationand the accompanying drawings.

SUMMARY OF THE INVENTION

To accomplish these and other objects, MOSFETs are provided as currentsources to supply operation currents to the bipolar transistors onlyduring the periods of their operation, there is provided a semiconductorintegrated circuit device featuring a high operation speed yet consumingreduced amounts of electric power.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a first embodiment wherein the presentinvention is adapted to a CMOS static-type RAM;

FIG. 2 is a circuit diagram of a reading circuit in the embodiment ofFIG. 1;

FIG. 3 is a timing chart for illustrating the operation of FIG. 2;

FIG. 4 is a circuit diagram of another embodiment wherein the presentinvention is adapted to a bipolar-type RAM; and

FIG. 5 is a block diagram showing a further power consumption reducingarrangement in accordance with the present invention.

DETAILED DESCRIPTION Embodiment 1

FIG. 1 shows a circuit diagram of a first embodiment in which thepresent invention is adapted to a CMOS static-type RAM. Though there isno particular limitation, the RAM of the same drawing is formed on asemiconductor substrate such as of a single silicon crystal inaccordance with well-known techniques for producing bipolar (Bi) andCMOS (complementary MOS) integrated circuits (ICs). Terminals A_(x),A_(y), D_(in), D_(out), WE and CS serve as external terminals.Incidentally, power supply terminals are omitted in the drawing. Thoughthere is no particular limitation, the CMOS static-type RAM of thisembodiment has a memory capacity of about 64 kilo-bits. In order toreduce the stray capacitance that resides in a common data line thatwill be mentioned later, the memory array is divided into four blocks.

A concrete circuit of memory cell MC is shown representatively. Namely,the memory cell consists of memory (drive) MOSFETs Q1 and Q2 of whichthe gates and drains are coupled in a crossing manner (in a latchedform), and high resistances R1 and R2 formed by polycrystalline siliconlayers for holding the data, that are provided between the drains of theMOSFETs Q1, Q2 and a power-source voltage V_(DD). Transfer gate MOSFETsQ3 and Q4 are provided between the commonly connected points of MOSFETsQ1, Q2 and the complementary data lines (or digit lines) D0, Othermemory cells MC have also been constructed in the same manner as above.These memory cells MC are arranged in the form of a matrix to constitutea memory array M-ARY0 that is representatively shown in FIG. 1. Namely,gates of the transfer gate MOSFETs Q3, Q4 of memory cells arranged inthe same row are commonly connected to their corresponding word lines W1and W2, and input/output terminals of memory cells arranged in the samecolumn are connected to their corresponding pairs of complementary datalines D0, D0 and D1, D1.

In order to reduce the power consumption of the memory cells MC, theresistor R1 has a resistance which is as high as that necessary for thegate voltage of the MOSFET Q2 to be maintained higher than a thresholdvoltage thereof when the MOSFET Q1 is rendered non-conductive.Similarly, the resistor R2 also has a high resistance. In other words,the resistor R1 has the ability to supply an electric current to such adegree that the data or electric charge stored in the gate capacity (notshown) of MOSFET Q2 is not discharged by a drain leakage current ofMOSFET Q1.

According to this embodiment, the memory cell MC is constituted byn-channel MOSFETs and polycrystalline silicon resistance elements asdescribed above, though the memory array is produced by the CMOS-ICtechnique. This helps reduce the sizes of memory cells and memory arraycompared with when p-channel MOSFETs are used instead of thepolycrystalline silicon resistance elements. That is, thepolycrystalline silicon resistors can be formed as a unitary structuretogether with the gate electrodes of driving MOSFETs Q1, Q2, and theirsizes can be reduced, too. Unlike the case of using p-channel MOSFETs,furthermore, large spacing distances are not required from the drivingMOSFETs Q1, Q2 and, hence, useless blank portions are not formed.

In the figure, the word line W1 is selected by a driving circuit DV1which receives a select signal formed by an X-address decoder X-DCR. Thesame also holds true for the other word line W2.

The X-address decoder X-DCR is constituted by NOR gate circuits G1, G2and so on that resemble one another. The inputs of these NOR gatecircuits G1, G2 and so on receive internal complementary address signalsin predetermined combinations, the internal complementary addresssignals being produced by the X-address buffer X-ADB that receivesexternal address signals A_(x) supplied from a suitable circuit that isnot shown.

Though there is no particular limitation, the pairs of data lines D0, D0and D1, D1 in the memory array M-ARY0 are connected to common data linesCD0, CD0 via column switching circuits constituted by transfer gateMOSFETs Q9, Q10, Q11 and Q12 for select data lines. To the common datalines CD0, CD0, there are connected input terminals of a reading circuitR and output terminals of a writing circuit W. Common data lines ofother memory arrays M-ARY0 to M-ARY3 that are not shown, have also beenconnected to their corresponding input terminals of the reading circuitR and to their corresponding output terminals of the writing circuit W.The output terminal of the reading circuit R sends a read signal to thedata output terminal D_(out), and a write data signal is applied fromthe data input terminal D_(in) to the input terminal of the writingcircuit W.

Select signals Y1, Y2 are supplied from a Y-address decoder Y-DCR to thegates of MOSFETs Q9, Q10, Q11 and Q12 that constitute theabove-mentioned column switching circuits. The Y-address decoder Y-DCRare constituted by NOR gate circuits G3, G4 and so on that resemble oneanother. To the input terminals of these NOR gate circuits G3, G4 areapplied internal complementary address signals in predeterminedcombinations, the internal complementary address signals being producedby the Y-address buffer Y-ADB that receives external address signalsA_(y) from a suitable circuit that is not shown.

A control circuit CON produces an internal control timing signal uponreceipt of control signals from the external terminals WE, CS.

Though there is no particular limitation in this embodiment, an internalchip select signal CS of the non-select condition which is formed by thecontrol circuit CON and which has the high level when the chip has notbeen selected is applied to the input terminals of the NOR gate circuitsG1, G2 and so on constituting the X-address decoder X-DCR, so that allof the word lines are placed under the non-selected condition. Thisprevents a direct current from flowing through a load MOSFET Q5 of thedata line, the transfer gate MOSFET Q3 of a memory cell MC connected toany word line that has been selected, and a memory MOSFET Q1 that hasbeen rendered conductive, when the chip has not been selected.

FIG. 2 is a circuit diagram of the reading circuit according to theembodiment of the present invention.

In this embodiment, use is made of bipolar transistors (differentialtransistors) T1, T2 of a differential form as a sense amplifier SA0which amplifies a read signal from the memory array M-ARY0. That is, theread voltages of a memory cell appearing on the common data lines CD0,CD0 are supplied to bases of the differential transistors T1, T2. Ann-channel MOSFET Q13 which receives an operation timing signal φ_(pa0)is connected to common emitters of the differential transistors T1, T2.Another memory array M-ARY3 which is representatively shown is alsoequipped with a sense amplifier SA3 that consists of similardifferential transistors T3, T4, and an n-channel MOSFET Q14. Thecorresponding collectors of the differential transistors T1, T2, T3 andT4 and so on are commonly connected to a pair of input terminals of themain amplifier MA that will be described later.

Operation timing signals φ_(pa0), φ_(pa3) supplied to the gates ofMOSFETs Q13, Q14 connected to common emitters of the differentialtransistors, are formed by NOR gate circuits G5, G6 that receive a readcontrol signal WE+CS which level is rendered to low level (logical "0")when the chip is selected and is placed under the read condition. GatesG5 and G6 also receive complementary address signals axi, ayi thatselect the memory arrays M-ARY0 to M-ARY3. Therefore, only a MOSFETwhich forms an operation current for a sense amplifier SA correspondingto a memory array that is selected to effect the reading operation, isturned on, and MOSFETs of the remaining three sense amplifiers SA areturned off.

Collectors of the differential transistors T1, T2, T3 and T4constituting the common sense amplifiers SA0 to SA3 are connected toemitters of the base-grounded amplifier transistors T5, T6 whichconstitute a circuit of the initial stage of a main amplifier MA. Basesof these transistors T5, T6 are served with a bias voltage formed by thenext bias circuit. Namely, serially connected diodes D1, D2 for shiftingthe level of the power-source voltage V_(DD), and an n-channel MOSFETQ16 for flowing a bias current, are connected in series between thepower-source voltage V_(DD) and a point of ground potential. Further, ann-channel MOSFET Q23 is connected in parallel with the diode D1, and,though not specifically limited, the gate of the MOSFET Q23 is servedwith a read control signal WE+CS which assumes the low level during thereading operation. N-channel MOSFETs Q15, Q17 are connected to theemitters of the transistors T5, T6 to form bias currents therefore. Thegates of these MOSFETs Q15, Q17 are served with a control signal WE·CSwhich assumes the high level during the reading operation. Therefore,the MOSFETs Q15 to Q17 are turned on only during the reading operationto form bias currents, respectively.

P-channel MOSFETs Q20, Q21 and n-channel MOSFETs Q22, Q24 are connectedin parallel, as load means between the power-source voltage V_(DD) andthe collectors of the transistors T5, T6. The p-channel MOSFETs Q20, Q21are rendered conductive at all times since their gates are always servedwith ground potential of the circuit, and the gates of the n-channelMOSFETs Q22, Q24 are served with the read control signal WE+CS.

Collector outputs of these transistors T5, T6 are transmitted to a dataoutput buffer DOB via emitter-follower transistors T7, T8. The emittersof the transistors T7, T8 are connected to n-channel MOSFETs Q18, Q19that form operation currents therefore and are served with the readcontrol signal WE·CS.

Operation of the circuit of this embodiment will be described below withreference to a timing chart of FIG. 3.

In the reading operation, a write enable signal WE is set to the highlevel, and a chip select signal CS is set to the low level. Therefore, aread control signal WE·CS becomes the high level, and an inverted signalWE+CS thereof becomes the low level (not shown). Accordingly, if theaddress signals axi, ayi supplied at this time assume the low level, theNOR gate circuit G5 is opened to produce an output signal φ_(pa0) of thehigh level which renders the MOSFET Q13 conductive. An operation currentflows into the differential transistors T1, T2, and the read signal fromthe memory array M-ARY0 is amplified and is produced through thecollectors.

On the other hand, since the control signal WE·CS of the main amplifierMA becomes the high level, MOSFETs Q15 to Q19 constituting the currentsources are rendered conductive to flow operation currents into thetransistors T5 to T8. Therefore, the output signals of the senseamplifier SA0 are supplied to a data output buffer DOB which is notshown, and a read output signal D_(out) is obtained from the externalterminal.

With regard to sense amplifiers SA1 to SA3 of other memory arrays M-ARY1to M-ARY3, the operation timing signals φ_(pa1) to φ_(pa3) become thelow level, and MOSFETs Q14 and the like that form operation currents,are rendered nonconductive. Therefore, the sense amplifiers SA1 to SA3establish the condition of high output impedance. Hence, the mainamplifier MA is served with only the electric current produced by theselected memory array M-ARY0.

In the writing operation, the write enable signal WE is set to the lowlevel as indicated by a broken line in FIG. 3, so that the controlsignal WE·CS becomes the low level and its inverted signal WE+CS becomesthe high level. Therefore, MOSFETs Q13 to Q19 for forming operationcurrents for the amplifier transistors of the sense amplifiers SA0 toSA3 and of the main amplifier MA, are all rendered nonconductive toinhibit their operation. In this case, depending upon the conductivecondition of MOSFET Q23, the bias voltage of the circuit of the initialstage of the main amplifier MA becomes nearly equal to V_(DD) -V_(f)(V_(f) denotes a forward voltage of the diode D2). Further, n-channelMOSFETs Q22 and Q24 that serve as load means are turned on to raise thebase potential of the emitter-follower transistors T7, T8, and p-channelMOSFETs (not shown) that constitute a circuit in the input stage of thedata output buffer circuit DOB are rendered nonconductive.

Embodiment 2

FIG. 4 is a circuit diagram of a second embodiment in which the presentinvention is adapted to a bipolar-type RAM. The RAM of the figure isformed on a semiconductor substrate such as a single silicon crystal bya technique for manufacturing semiconductor integrated circuits similarto that used in FIG. 1 Terminals XA0 to XAk, YA0 to YAl, D_(out),D_(in), CS, WE, -V_(ee) and GND serve as external terminals. The figure,however, does not show power-source terminals -V_(ee) and GND. Unlikethe circuit of the embodiment of FIG. 1, furthermore, transistors aredenoted by Q, and MOSFETs are denoted by M.

Among a plurality of memory cells constituting a memory array M-ARY, aconcrete circuit of only one memory cell is shown in the figure. Thoughthere is no particular limitation, in one memory cell, use is made of aflip-flop circuit which consists of drive npn-type transistors Q12, Q13of which the bases and collectors are coupled in a crossing manner, andpnp-type transistors Q14, Q15 that are connected to their collectors.Though there is no particular limitation, the drive npn-type transistorsQ12, Q13 are of the multi-emitter construction. The emitters on one sideare commonly connected together, and the emitters of the other sideserve as input/output terminals of a memory cell and are connected to apair of complementary data lines D0, D0 that are representatively shown.The drive npn-type transistors Q12, Q13 may be constituted by twotransistors of which the base and collectors are commonly connectedtogether. Further, the load transistors Q14, Q15 may be replaced by loadresistors and clamping diodes that are connected in parallel with eachother. The common emitters of the load transistors Q14, Q15 areconnected to a word line W0 which is shown representatively.

With the above-mentioned memory cell as a center, similar memory cells(represented by a black box) of a number of m are arranged along thelaterally running row and are connected to the word line W0. Thelaterally stretching row is provided with a holding current line ST0which corresponds to the word line W0, and the commonly connectedemitters of one side of drive transistors Q12, Q13 of the memory cellare connected thereto. Memory cells are also connected in the samemanner as above with respect to another representatively shown row (wordline Wn, holding current line STn). The holding current lines ST0, STnare provided with constant-current source Ist (not shown) that supplyholding currents to the memory cells.

Further, the similarly constructed memory cells are arranged in a numberof n along the vertical column, and input/output terminals thereof arecommonly connected to the complementary data lines D0, D0. Thus, memorycells are arranged in a number of m×n along the rows and columns toconstitute a memory array M-ARY.

The word lines W0, Wn which are representatively shown are selected ornot selected by word line drive transistors Q16, Q17 that receiveaddress decoded signals X0, Xn which are produced by the X-addressdecoder X-DCR.

Address signals supplied from a suitable circuit not shown are inputtedto the address buffers XAB0 to XABk via external terminals XA0 to XAk.These address buffers CAB0 to XABk form noninverted address signals andinverted address signals depending upon the input address signals, andsend them to the X-address decoder X-DCR. Then, the X-address decoderX-DCR forms a word line select signal to select a word line.

In this embodiment, the complementary data lines D0, D0 representativelyshown are connected, via transistors Q18, Q20 that serve as columnswitches, to n-channel MOSFETs M1 and M3 that are also provided commonlyfor other complementary data lines not shown, and that are turned on byan internal chip select signal CS to form a read/write current Ir. Anaddress decoded signal Y0 produced by the Y-address decoder Y-DCR isapplied to the bases of the transistors Q18 and Q20 that work as columnswitches. Namely, address signals supplied from a suitable circuit notshown are inputted to the address buffers YAB0 to YABl via externalterminals YA0 to YAl. The address buffers YAB0 to YABl producenoninverted address signals and inverted address signals according tothe input address signals and send them to the Y-address decoder Y-DCR.Therefore, the Y-address decoder Y-DCR forms a data line select signalto select a pair of complementary data lines. According to thisembodiment, though there is no particular limitation, a bias circuit issubsequently provided to apply a predetermined bias voltage to datalines that have not been selected. That is, a diode D3 and a resistor R6are connected in series between the base and the collector of atransistor Q21 of which the collector is served with ground potential ofthe circuit. The diode D3 and resistor R6 connected in series areconnected, via a transistor Q19, to an n-channel MOSFET M2 that producesa current Ir like the one mentioned above. Though there is no particularlimitation, the transistor Q21 is of the multi-emitter construction, andis connected to the complementary data lines D0, D0.

A source of a very small constant current is coupled to thecomplementary data lines D0, D0. Namely, a very small constant currentis absorbed at all times by transistors Q23, (Q24) which receive aconstant voltage b1 through the bases thereof and which have resistorsconnected to the emitters thereof.

Therefore, the data line which is not selected is biased by a voltagewhich is nearly equal to the sum of a forward voltage of the diode D3and a voltage across the base and emitter of the transistor Q21. Whenthe complementary data lines D0, D0 are selected, the current Irproduced by the MOSFET M2 that is rendered conductive flows into theresistor R6 via the transistor Q19. Therefore, the transistor Q21 isrendered non-conductive, and potentials of the complementary data linesD0, D0 are determined with the stored data in the selected memory cell.

Emitters of current switching transistors Q7, Q6 are coupled to thecomplementary data lines D0, D0 in order to write/read the data relativeto a memory cell of a row that is shown representatively. Collectoroutputs of these transistors Q7, Q6 are sent to the input terminals ofthe main amplifier MA which effects the amplification operation andforms an output signal that meets the input level of a data outputbuffer DOB constituted by ECL (emitter coupled logic). The data outputbuffer DOB produces a read output signal that will be sent through theexternal terminal D_(out). The main amplifier MA is constructedsimilarly to the main amplifier of the embodiment of FIG. 1.

Output voltages V1, V2 of a writing circuit WA are applied to the basesof the current switching transistors Q7, Q6. The writing circuit WAwhich forms the output voltages V1, V2 is constituted by differentialtransistors Q1 to Q3, a constant-current source provided to the commonemitters thereof, resistors R1, R2 provided to the collectors of thetransistors Q1, Q2, and a resistor R3 provided between the groundpotential and a point where the resistors R1, R2 and the collector ofthe transistor Q3 are commonly connected together. Bases of thetransistors Q1, Q2 are served with write data signals d_(in), d_(in)sent from a data input buffer DIB that will be described later, and baseof the transistor Q3 is served with an internal write enable signal wesent from a control circuit CONT that will be described later.

According to this embodiment, though there is no particular limitation,the data input buffer DIB is constructed as described below, so thatnoise will not generate in the output voltages V1, V2 of the writingcircuit WA according to the change of levels of the input data signalsd_(in), d_(in) during the writing operation. Namely, a transistor Q8receives a write data signal supplied through the external terminalD_(in), and a transistor Q9 is impressed with a reference voltage Vb2through the base thereof to discriminate the input signal, and thesetransistors Q8 and Q9 are connected together in a differential manner.Resistors R4 and R5 are connected to the collectors of thesedifferential transistors Q8 and Q9. Collector outputs of thedifferential transistors Q8 and Q9 are applied to bases ofemitter-follower transistors Q25, Q26, and data signals d_(in) andd_(in) are sent from the emitters of these transistors Q25 and Q26 tothe writing circuit WA. The collector of a differential transistor Q10is connected to the common emitters of the differential transistors Q8and Q9, so that the data signals d_(in) and d_(in) will not changedepending upon the signals from the external terminal D_(in) during thereading operation. A reference voltage Vb3 is applied to the base of thetransistor Q10 to discriminate the internal write enable signal we. Theinternal write enable signal we is applied to the base of the transistorQ11 which is connected in a differential manner relative to thetransistor Q10. The collector of the transistor Q11 is connected to thecollectors of the differential transistors Q8 and Q9 via diodes D1 andD2.

According to this embodiment, although there is no particularlimitation, the operation currents I1 to I4 for the transistors Q1 to Q5and for the transistors Q8, Q11, Q25 and Q26 are formed by n-channelMOSFETs M4 to M9 that are rendered conductive by an internal chip selectsignal cs, in order to reduce the ineffective current when the chip isnot being selected.

The control circuit CONT which receives control signals supplied via theexternal terminals WE and CS, produces an operation control signal forthe data output buffer DOB, the internal write enable signal we thatwill be supplied to the writing circuit WA and to the data input bufferDIB, and the internal chip select signal cs. Internal circuitry forforming these signals can be constructed utilizing well-establishedprinciples for making such control circuitry.

When the control signal CS is set to the low level in order to selectthe chip, the control circuit CONT produces an internal chip selectsignal cs of the high level. On the other hand, when the control signalCS is set to the high level to place the chip under the nonselectedcondition, the control circuit CONT produces an internal chip selectsignal cs of the low level.

The reading operation is performed when the terminal WE is set to thehigh level and the terminal CS is set to the low level. In the datainput buffer DIB in this case, the write enable signal we assumes thehigh level since the terminal WE assumes the high level. Therefore, thetransistor Q10 is rendered nonconductive, the transistor Q11 is renderedconductive, and the electric current I4 flows being divided intoone-half into the resistors R4 and R5 via diodes D1, D2. Therefore,irrespective of the signals from the external terminal D_(in), theoutput level is fixed to the intermediate level, and noise caused by thechange of level at the external terminal D_(in) is prevented fromappearing in the read reference voltage V1, V2 (V_(refc)) in the readingoperation.

According to this embodiment, the read/write current Ir for the memoryarray M-ARY, and operation current for the writing circuit WA that isrepresentatively shown, are produced by the MOSFETs which are operatedby the internal chip select signal cs. Therefore, the ineffectivecurrent is prevented from flowing wastefully when the chip is notselected. Current-source circuits for producing operation currents forthe peripheral circuits, i.e., for the address decoders X-DCR, Y-DCR,are also constituted by the same MOSFETs that will be renderedconductive upon receipt of the internal chip select signal cs, in orderto reduce the ineffective current. When the MOSFETs for producingoperation currents for the address decoders X-DCR, Y-DCR are renderednonconductive under the condition where the chip is not selected, theoutput signals thereof take a non-select level.

According to this embodiment, the MOSFETs for producing operationcurrents for the transistors are turned on or off responsive to a chipselect signal depending upon whether the chip is selected or notselected, thereby to reduce the current from wastefully flowing underthe condition in which the chip is not selected. Furthermore, as shownin FIG. 5, provision may be made of a circuit 100 for detecting thechange of address signals, and a circuit 200 which, responsive to thedetection outputs thereof, produces timing signals to time-seriallyoperate the address buffer, address decoder, memory array M-ARY, readingcircuit and writing circuit in the order mentioned, so that each of thecircuit blocks is time-serially operated only at required timings by theoperating timing signals, under the condition where the chip isselected. In this case, the consumption of current can be reduced evenunder the condition where the chip is selected. With regard to such anarrangement, it is noted that construction of the circuit 100 fordetecting the change of address signals is well known, and its detailsare not described here. Similarly, construction of a timing signalgenerator 200 to produce time-serial timing signals can be doneaccording to well-known design principles for making time circuitry. Forinstance, the timing signal generator 200 is comprised in combination ofCMOS slatic inverters for producing delay signals and CMOS stacit gatecircuits for producing the timing signals.

In the aforementioned embodiments 1 and 2, when the operation currentsof the bipolar transistors are to be formed, the MOSFETs are operated inthe saturated region. Therefore, the MOSFETs produce a nearly constantoperation current for the bipolar transistors.

In the embodiment 1, furthermore, when the address buffer ADB and theaddress decoder DCR are constituted by MOSFETs and bipolar transistorsin order to increase the operation speed (e.g., when a required logiccircuit is constituted by the MOSFETs, and a driver circuit constitutedby bipolar transistors is provided to receive the output signal of thelogic circuit, so that the subsequent stage can be driven at a highspeed), operation currents for the bipolar transistors are produced bythe MOSFETs, and these MOSFETs are further controlled in the same manneras mentioned earlier, such that the RAM consumes reduced amounts ofelectric power while still featuring an increased operation speed. Inthis case, furthermore, provision may be made of a circuit for detectingthe change of address signals like the aforementioned circuit 100 fordetecting the change of address signals, as well as a timingsignal-forming circuit like the aforementioned circuit 200 for formingtiming signals, in order to time-serially operate the address buffer,decoder, sense amplifier, writing circuit and the reading circuit in theorder mentioned only at required timings, in the same manner asmentioned earlier. This makes it possible to reduce the consumption ofelectric power even under the condition where the chip is selected.Preferably, the time-series outputs of the circuit 200 are coupled tothe MOSFETs of the various peripheral circuits (i.e., address buffers,decoders, etc.) to provide the time-series operation by controlling theturn-on and turn-off time of the MOSFETs which serve as current sourcesfor the bipolar transistor.

By virtue of the construction set forth above, the following advantagescan be achieved:

(1) MOSFETs that will be turned on only during the periods of operationare used to produce operation currents for the bipolar transistors thatrequire relatively large operation currents. Therefore, wastefulconsumption of electric current is reduced, and the consumption ofelectric power is greatly reduced.

(2) Since differential transistors consisting of bipolar transistors areused as a sense amplifier in a CMOS static RAM, only a very smallelectric current is allowed to flow into the data lines in reverseproportion to the current amplification factor. In other words,operation current of the sense amplifier can be increased even when thesize of the memory cells is reduced to decrease the current drivingability. This makes it possible to accomplish a high reading operation.

(3) Since MOSFETs that will be turned on only during the readingoperation are employed to produce operation currents for thedifferential transistors that constitute a sense amplifier, wastefulconsumption of electric current is reduced. This helps maintain theadvantage of low power consumption inherent in the CMOS static RAM, anda device employing bipolar transistor circuits can be realized which ispowered by batteries and the like.

(4) The memory array M-ARY is divided into a plurality of blocks, andthe sense amplifier is provided with an address decoder function, suchthat the consumption of electric power is further reduced and theoperation speed is further increased.

(5) Since MOSFETs that will be turned on only when the chip is selectedare used to produce reading and writing currents for the memory arrayM-ARY in the bipolar RAM and to produce currents for such peripheralcircuits as the writing circuit and the reading circuit, it is madepossible to greatly reduce the wasteful consumption of electric currentwhen the chip is not being selected.

(6) MOSFETs are used to produce operation currents for the circuitblocks in the RAM, and the circuit blocks are time-serially operated atrequired timings responsive to change detection signals of addresssignals. Therefore, wasteful consumption of electric current can bereduced under the condition in which the chip is selected.

The invention accomplished by the inventor was concretely described inthe foregoing by way of embodiments. However, it should be noted thatthe invention is in no way limited to the above embodiments only but canbe variously modified within a scope that does not depart from the gistof the invention. For instance, the resistors for holding data in thememory cells of the embodiment of FIG. 1 may be replaced by p-channelMOSFETs. In place of the CMOS circuit, furthermore, either the n-channelMOSFETs or p-channel MOSFETs may be employed. Further, the peripheralcircuits and the timing control can be realized in a variety of otherways.

Moreover, the gates of p-channel MOSFETs which produce operationcurrents for the bipolar transistors may be served with a predeterminedconstant voltage at the timings of operation.

The foregoing description has dealt with the case in which the inventionaccomplished by the inventor was adapted to the CMOS static RAM and tothe bipolar RAM that served as the background of the invention. Theinvention, however, should in no way be limited thereto only, but can bewidely adapted to semiconductor integrated circuit devices that includebipolar transistors for amplifying and transmitting signals and acircuit that produces operation currents for the bipolar transistors.

I claim:
 1. A semiconductor integrated circuit device comprising bipolartransistors that generate output signals at their collectors only duringa period of their operation and one or more first MOSFETs controlled bya control signal to be conductive to serve as current sources to supplyoperation currents to said bipolar transistors only during the periodsof their operation so that said bipolar transistors generate said outputsignals only when said first MOSFETs are rendered conductive by saidcontrol signal,wherein said bipolar transistors are differentialtransistors which receive read signals from memory cells and whereinsaid first MOSFETs are coupled to common emitters of said differentialtransistors to form said operation currents for said bipolar transistorsaccording to reach control signals applied to said first MOSFETs as saidcontrol signal, and wherein said collector output signal of saiddifferential transistors is amplified by an amplifier circuit which iscomprised of a bipolar transistor that works as an amplifier element anda second MOSFET which is turned on only during an operation periodthereof and which constitutes a current source for said amplifiercircuit bipolar transistor.
 2. A semiconductor integrated circuit deviceaccording to claim 1, wherein said memory cells are static memory cellsconstructed of MOSFETs.
 3. A semiconductor integrated circuit deviceaccording to claim 1, wherein said operation currents for said bipolartransistors are formed only in response to said control signals appliedto said first MOSFETs.
 4. A semiconductor integrated circuit deviceaccording to claim 3, further comprising control means for providingsaid control signal, wherein said first MOSFETs receive said controlsignal only during a read operation.
 5. A semiconductor integratedcircuit device comprising:a differential circuit including first andsecond bipolar transistors which receive at respective bases thereofinput signals and generate at respective collectors thereof outputsignals in response to the input signals, emitters of said first andsecond bipolar transistors being coupled to each other to form a commonemitter; and a first MOSFET to supply operating current to saiddifferential circuit, said first MOSFET having a source-drain pathcoupled to said common emitter to supply said operating current for saiddifferential circuit in response to a control signal applied to a gateof said first MOSFET; storage means for storing data therein and coupledto said differential circuit to supply said input signals in response tothe data stored in said storage means to the bases of said first andsecond bipolar transistors, respectively; and control means forproviding said control signal, said control means being coupled to thegate of said first MOSFET, wherein said control means provides saidcontrol signal for the gate of said first MOSFET to operate saiddifferential circuit when said storage means is selected for readoperation, wherein said differential circuit is a sense circuit forsensing said input signals and wherein said control means is responsiveto an address signal and provides said control signal for the gate ofsaid first MOSFET to operate said sense circuit when said storage meansis selected for the read operation.
 6. A semiconductor integratedcircuit device according to claim 5, wherein the input signals includecomplementary signals that have opposite phases to each other.
 7. Asemiconductor integrated circuit device according to claim 5, whereinsaid storage means includes a memory cell constructed of at least oneMOSFET.
 8. A semiconductor integrated circuit device according to claim5, wherein said storage means includes a static memory cell constructedof a plurality of MOSFETs.
 9. A semiconductor integrated circuit deviceaccording to claim 5, wherein said control means provides said controlsignal when a write enable signal indicates a read condition to read thedata stored in said storage means by said sense circuit.
 10. Asemiconductor integrated circuit device according to claim 5, whereinsaid control means provides said control signal when a chip selectsignal indicates a chip select condition to read the data stored in saidstorage means by said sense circuit.
 11. A semiconductor integratedcircuit device according to claim 9, wherein said control means providessaid control signal when a chip is selected for a read operation.
 12. Asemiconductor memory device comprising:a memory array including aplurality of word lines, a plurality of data lines and a plurality ofmemory cells coupled to said plurality of word and data lines so thateach memory cell is coupled to a word line and at least one data line,said memory array further including means for providing a pair ofsignals in response to data stored in a selected one of said pluralityof memory cells; selection means for selecting one of said plurality ofmemory cells, which is coupled to said memory array and which is coupledto receive address signals that indicate an address of said one of saidplurality of memory cells in said memory array; a read circuit coupledto receive said pair of signals of said memory array, said read circuitincluding a pair of bipolar transistors coupled to form a differentialcircuit and a MOSFET to provide operating current to said differentialcircuit, said pair of bipolar transistors having bases coupled toreceive said pair of signals and a common emitter to be coupled to saidMOSFET, said MOSFET having a source-drain path coupled to said commonemitter; and control means responsive to at least one of the addresssignals for providing a control signal to a gate of said MOSFET tooperate said MOSFET, so that said operating current for saiddifferential circuit is provided in response to receipt of said controlsignal by said MOSFET and so that said pair of bipolar transistorsprovide output signals at collectors thereof according to said pair ofsignals received by the bases thereof.
 13. A semiconductor memory deviceaccording to claim 7, wherein said plurality of memory cells includestatic memory cells constructed of MOSFETs.
 14. A semiconductor memorydevice according to claim 7, wherein each of said plurality of memorycells includes a pair of cross-coupled MOSFETs and resistor means.
 15. Asemiconductor memory device according to claim 7, wherein saiddifferential circuit is a sense circuit.
 16. A semiconductor memorydevice according to claim 7, wherein said pair of signals generated fromsaid memory array include complementary signals that have oppositephases to one another.
 17. A semiconductor memory device according toclaim 7, wherein said MOSFET is turned on in accordance with saidcontrol signal only when said memory array is selected for a readoperation.
 18. A semiconductor memory device according to claim 7,wherein said control signal includes a timing signal for operating saiddifferential circuit.
 19. A semiconductor memory device according toclaim 18, wherein said control signal includes a pulse signal.
 20. Asemiconductor memory device according to claim 7, wherein said controlmeans includes a gate circuit.
 21. A semiconductor memory deviceaccording to claim 7, wherein said control means is coupled to receiveat least one internal control signal in accordance with at least oneexternal control signal applied from the outside of said semiconductormemory and wherein said control means provides said control signal forsaid MOSFET in accordance with said internal control signal indicatingthat said memory array is selected for a read operation.
 22. Asemiconductor memory device according to claim 7, wherein said controlsignal includes a predetermined voltage which is provided by saidcontrol means.
 23. A semiconductor memory device according to claim 7,wherein said control means provides said control signal only during aread operation.